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iOS 邊下邊播的實現(xiàn)代碼

 更新時間：2017年11月13日 11:52:58   投稿：mrr  
在之前項目中使用的是AVPlayer直接播放URL地址，但是不知道是相機的wifi不夠穩(wěn)定還是代碼的問題，app總是出現(xiàn)緩沖卡頓。后來考慮改成邊下邊播模式，下面小編給大家?guī)砹薸OS 邊下邊播的實現(xiàn)代碼，需要的朋友參考下吧

項目中之前使用的是AVPlayer直接播放URL地址，但是不知道是相機的wifi不夠穩(wěn)定還是代碼的問題，app總是出現(xiàn)緩沖卡頓，就考慮改寫成邊下邊播的模式，查過了許多資料，發(fā)現(xiàn)大部分都是用的同一種方法

AVAssetResourceLoaderDelegate 代理方法，來看看如何實現(xiàn)

首先要實現(xiàn)兩個必須的代理方法

AVAssetResourceLoaderDelegateObjective-C
#pragma mark - AVAssetResourceLoaderDelegate
//開始加載
- (BOOL)resourceLoader:(AVAssetResourceLoader *)resourceLoader shouldWaitForLoadingOfRequestedResource:(AVAssetResourceLoadingRequest *)loadingRequest {
  [self addLoadingRequest:loadingRequest];
  return YES;
}
//取消加載
- (void)resourceLoader:(AVAssetResourceLoader *)resourceLoader didCancelLoadingRequest:(AVAssetResourceLoadingRequest *)loadingRequest {
  [self removeLoadingRequest:loadingRequest];
}
#pragma mark - AVAssetResourceLoaderDelegate
//開始加載
- (BOOL)resourceLoader:(AVAssetResourceLoader *)resourceLoader shouldWaitForLoadingOfRequestedResource:(AVAssetResourceLoadingRequest *)loadingRequest {
  [self addLoadingRequest:loadingRequest];
  return YES;
}
//取消加載
- (void)resourceLoader:(AVAssetResourceLoader *)resourceLoader didCancelLoadingRequest:(AVAssetResourceLoadingRequest *)loadingRequest {
  [self removeLoadingRequest:loadingRequest];
}

然后要定義一個下載類，其實就是分段下載數(shù)據(jù)的下載器

AVAssetResourceLoaderDelegateObjective-C
- (void)start {
  NSMutableURLRequest * request = [NSMutableURLRequest requestWithURL:[self.requestURL originalSchemeURL] cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:RequestTimeout];
  if (self.requestOffset > 0) {
    [request addValue:[NSString stringWithFormat:@"bytes=%ld-%ld", self.requestOffset, self.fileLength - 1] forHTTPHeaderField:@"Range"];
  }
  self.session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[NSOperationQueue mainQueue]];
  self.task = [self.session dataTaskWithRequest:request];
  [self.task resume];
}
#pragma mark - NSURLSessionDataDelegate
//服務(wù)器響應(yīng)
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler {
  if (self.cancel) return;
  SRQLog(@"response: %@",response);
  completionHandler(NSURLSessionResponseAllow);
  NSHTTPURLResponse * httpResponse = (NSHTTPURLResponse *)response;
  NSString * contentRange = [[httpResponse allHeaderFields] objectForKey:@"Content-Range"];
  NSString * fileLength = [[contentRange componentsSeparatedByString:@"/"] lastObject];
  self.fileLength = fileLength.integerValue > 0 ? fileLength.integerValue : response.expectedContentLength;
  if (self.delegate && [self.delegate respondsToSelector:@selector(requestTaskDidReceiveResponse)]) {
    [self.delegate requestTaskDidReceiveResponse];
  }
}
//服務(wù)器返回數(shù)據(jù) 可能會調(diào)用多次
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data {
  if (self.cancel) return;
  //SRQLog(@"收到響應(yīng)了: %@",data);
  self.cacheLength += data.length;
  if (self.delegate && [self.delegate respondsToSelector:@selector(requestTaskDidUpdateCache)]) {
    [self.delegate requestTaskDidUpdateCache];
  }
}
//請求完成會調(diào)用該方法，請求失敗則error有值
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {
  if (self.cancel) {
    SRQLog(@"下載取消");
  }else {
    if (error) {
      if (self.delegate && [self.delegate respondsToSelector:@selector(requestTaskDidFailWithError:)]) {
        [self.delegate requestTaskDidFailWithError:error];
      }
    }else {
      //可以緩存則保存文件
      if (self.cache) {
        [FileHandle cacheTempFileWithFileName:[NSString fileNameWithURL:self.requestURL]];
      }
      if (self.delegate && [self.delegate respondsToSelector:@selector(requestTaskDidFinishLoadingWithCache:)]) {
        [self.delegate requestTaskDidFinishLoadingWithCache:self.cache];
      }
    }
  }
}

- (void)start {
  NSMutableURLRequest * request = [NSMutableURLRequest requestWithURL:[self.requestURL originalSchemeURL] cachePolicy:NSURLRequestReloadIgnoringCacheData timeoutInterval:RequestTimeout];
  if (self.requestOffset > 0) {
    [request addValue:[NSString stringWithFormat:@"bytes=%ld-%ld", self.requestOffset, self.fileLength - 1] forHTTPHeaderField:@"Range"];
  }
  self.session = [NSURLSession sessionWithConfiguration:[NSURLSessionConfiguration defaultSessionConfiguration] delegate:self delegateQueue:[NSOperationQueue mainQueue]];
  self.task = [self.session dataTaskWithRequest:request];
  [self.task resume];
}
#pragma mark - NSURLSessionDataDelegate
//服務(wù)器響應(yīng)
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response completionHandler:(void (^)(NSURLSessionResponseDisposition))completionHandler {
  if (self.cancel) return;
  SRQLog(@"response: %@",response);
  completionHandler(NSURLSessionResponseAllow);
  NSHTTPURLResponse * httpResponse = (NSHTTPURLResponse *)response;
  NSString * contentRange = [[httpResponse allHeaderFields] objectForKey:@"Content-Range"];
  NSString * fileLength = [[contentRange componentsSeparatedByString:@"/"] lastObject];
  self.fileLength = fileLength.integerValue > 0 ? fileLength.integerValue : response.expectedContentLength;
  if (self.delegate && [self.delegate respondsToSelector:@selector(requestTaskDidReceiveResponse)]) {
    [self.delegate requestTaskDidReceiveResponse];
  }
}
//服務(wù)器返回數(shù)據(jù) 可能會調(diào)用多次
- (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveData:(NSData *)data {
  if (self.cancel) return;
  //SRQLog(@"收到響應(yīng)了: %@",data);
  self.cacheLength += data.length;
  if (self.delegate && [self.delegate respondsToSelector:@selector(requestTaskDidUpdateCache)]) {
    [self.delegate requestTaskDidUpdateCache];
  }
}
//請求完成會調(diào)用該方法，請求失敗則error有值
- (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task didCompleteWithError:(NSError *)error {
  if (self.cancel) {
    SRQLog(@"下載取消");
  }else {
    if (error) {
      if (self.delegate && [self.delegate respondsToSelector:@selector(requestTaskDidFailWithError:)]) {
        [self.delegate requestTaskDidFailWithError:error];
      }
    }else {
      //可以緩存則保存文件
      if (self.cache) {
        [FileHandle cacheTempFileWithFileName:[NSString fileNameWithURL:self.requestURL]];
      }
      if (self.delegate && [self.delegate respondsToSelector:@selector(requestTaskDidFinishLoadingWithCache:)]) {
        [self.delegate requestTaskDidFinishLoadingWithCache:self.cache];
      }
    }
  }
}

最后將拿到的數(shù)據(jù)塞進AVAssetResourceLoaderDelegate代理中，交還給AVPlayer，就可以播放了

AVAssetResourceLoaderDelegateObjective-C
- (BOOL)finishLoadingWithLoadingRequest:(AVAssetResourceLoadingRequest *)loadingRequest {
  //填充信息
  CFStringRef contentType = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, (__bridge CFStringRef)(MimeType), NULL);
  loadingRequest.contentInformationRequest.contentType = CFBridgingRelease(contentType);
  loadingRequest.contentInformationRequest.byteRangeAccessSupported = YES;
  loadingRequest.contentInformationRequest.contentLength = self.requestTask.fileLength;
  //讀文件，填充數(shù)據(jù)
  NSUInteger cacheLength = self.requestTask.cacheLength;
  NSUInteger requestedOffset = loadingRequest.dataRequest.requestedOffset;
  if (loadingRequest.dataRequest.currentOffset != 0) {
    requestedOffset = loadingRequest.dataRequest.currentOffset;
  }
  NSUInteger canReadLength = cacheLength - (requestedOffset - self.requestTask.requestOffset);
  NSUInteger respondLength = MIN(canReadLength, loadingRequest.dataRequest.requestedLength);
  //SRQLog(@"好不容易填充一次");
  [loadingRequest.dataRequest respondWithData:[FileHandle readTempFileDataWithOffset:requestedOffset - self.requestTask.requestOffset length:respondLength]];
  //如果完全響應(yīng)了所需要的數(shù)據(jù)，則完成
  NSUInteger nowendOffset = requestedOffset + canReadLength;
  NSUInteger reqEndOffset = loadingRequest.dataRequest.requestedOffset + loadingRequest.dataRequest.requestedLength;
  if (nowendOffset >= reqEndOffset) {
    [loadingRequest finishLoading];
    return YES;
  }
  return NO;
}
- (void)player{
    self.resouerLoader     = [[ResourceLoader alloc] init];
    self.asset = [AVURLAsset URLAssetWithURL:[self.videoUrl customSchemeURL] options:nil];
    [self.asset.resourceLoader setDelegate:self.resouerLoader queue:dispatch_get_main_queue()];
    _playerItem = [AVPlayerItem playerItemWithAsset:self.asset];
    _players = [AVPlayer playerWithPlayerItem:_playerItem];
}

- (BOOL)finishLoadingWithLoadingRequest:(AVAssetResourceLoadingRequest *)loadingRequest {
  //填充信息
  CFStringRef contentType = UTTypeCreatePreferredIdentifierForTag(kUTTagClassMIMEType, (__bridge CFStringRef)(MimeType), NULL);
  loadingRequest.contentInformationRequest.contentType = CFBridgingRelease(contentType);
  loadingRequest.contentInformationRequest.byteRangeAccessSupported = YES;
  loadingRequest.contentInformationRequest.contentLength = self.requestTask.fileLength;
  //讀文件，填充數(shù)據(jù)
  NSUInteger cacheLength = self.requestTask.cacheLength;
  NSUInteger requestedOffset = loadingRequest.dataRequest.requestedOffset;
  if (loadingRequest.dataRequest.currentOffset != 0) {
    requestedOffset = loadingRequest.dataRequest.currentOffset;
  }
  NSUInteger canReadLength = cacheLength - (requestedOffset - self.requestTask.requestOffset);
  NSUInteger respondLength = MIN(canReadLength, loadingRequest.dataRequest.requestedLength);
  //SRQLog(@"好不容易填充一次");
  [loadingRequest.dataRequest respondWithData:[FileHandle readTempFileDataWithOffset:requestedOffset - self.requestTask.requestOffset length:respondLength]];
  //如果完全響應(yīng)了所需要的數(shù)據(jù)，則完成
  NSUInteger nowendOffset = requestedOffset + canReadLength;
  NSUInteger reqEndOffset = loadingRequest.dataRequest.requestedOffset + loadingRequest.dataRequest.requestedLength;
  if (nowendOffset >= reqEndOffset) {
    [loadingRequest finishLoading];
    return YES;
  }
  return NO;
}
- (void)player{
    self.resouerLoader     = [[ResourceLoader alloc] init];
    self.asset = [AVURLAsset URLAssetWithURL:[self.videoUrl customSchemeURL] options:nil];
    [self.asset.resourceLoader setDelegate:self.resouerLoader queue:dispatch_get_main_queue()];
    _playerItem = [AVPlayerItem playerItemWithAsset:self.asset];
    _players = [AVPlayer playerWithPlayerItem:_playerItem];
}

注意：此方法服務(wù)器端最好支持Range頭，這樣才是分段下載。

總結(jié)

以上所述是小編給大家介紹的iOS 邊下邊播的實現(xiàn)代碼，希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會及時回復(fù)大家的。在此也非常感謝大家對腳本之家網(wǎng)站的支持！

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